PMC

¹³C-¹³C scalar coupling multiplets observed for Asp-α from ammonia-limited chemostat cultures of E. coli W3110 (left) and the Zwf mutant (right). The signals were extracted from the ω₁(¹³C) cross sections in the [¹³C,¹H]-COSY spectra. See the legend to Fig. for definitions of multiplet components. Aspartate corresponds directly to its metabolic precursor, oxaloacetate (OAA).

Specific rates of NADPH production and consumption in glucose (C)- and ammonia (N)-limited chemostat cultures of E. coli W3110, the Pgi mutant, and the Zwf mutant. NADPH production was contributed to by the oxidative PP pathway (solid bars), isocitrate dehydrogenase (cross-hatched bars), transhydrogenase (hatched bars), and malic enzyme (stippled bars). NADPH was consumed via biomass formation(stippled bars) and the transhydrogenase reaction (hatched bars).

¹³C-¹³C scalar coupling multiplets observed for C-4 of glucose from ammonia-limited chemostat cultures of E. coli W3110 (left) and the Pgi mutant (right). The signals were extracted from the ω₁(¹³C) cross sections in the [¹³C,¹H]-COSY spectra. As glucose C-4 exhibits scalar coupling constants identical to those of the adjacent carbons, the multiplets consist of a singlet (s), a doublet (d), and a triplet (t). The labeling data for glucose represent the labeling patterns of G6P.

Bioreaction network of E. coli central carbon metabolism. The arrows indicate the physiological directions of reactions. Fluxes to biomass building blocks are indicated by gray arrows. Abbreviations: F6P, fructose 6-phosphate; T3P, triose 3-phosphate; 3PG, 3-phosphoglycerate; PYR, pyruvate; ACoA, acetyl coenzyme A; 6PG, 6-phosphogluconate; S7P, seduheptulose 7-phosphate; OAA, oxaloacetate; ICT, isocitrate; AKG, α-ketoglutarate; SUC, succinate; FUM, fumarate; MAL, malate; GOX, glyoxylate; EPS, extracellular polysaccharide; ETH, ethanol; ACE, acetate; ex, extracellular.

¹³C-¹³C scalar coupling multiplets observed for aspartate from glucose-limited chemostat cultures of E. coli W3110 (left) and the Pgi mutant (right). The signals were extracted from the ω₁(¹³C) cross sections in the [¹³C,¹H]-COSY spectra. (A) Asp-α; (B) Asp-β. As indicated in panel A, the multiplets consist of a singlet (s), a doublet with a small coupling constant (Da), a doublet split by a larger coupling constant (db), and a doublet of doublets (dd). Aspartate corresponds directly to its metabolic precursor, oxaloacetate (OAA).

Metabolic flux distribution in chemostat cultures of E. coli W3110 under glucose-limited conditions (A) and ammonia-limited conditions (B), the Pgi mutant under glucose-limited conditions (C) and ammonia-limited conditions (D), and the Zwf mutant under glucose-limited conditions (E) and ammonia-limited conditions (F). The chemostats were operated at a dilution rate of 0.1 h⁻¹. The numbers in rectangles are the net fluxes determined. The flux values are expressed relative to the specific glucose uptake rate, which is indicated in parentheses (in millimoles per gram [dry weight] per hour). The arrows indicate the directions of the fluxes determined. The numbers in ellipses are the fluxes for withdrawal of precursor metabolites for biomass formation. For abbreviations, see the legend to Fig. .